WO1998011755A2

WO1998011755A2 - Process and device for increasing the reach of transmission paths between functional units of an isdn subscriber connection with a minimized band width

Info

Publication number: WO1998011755A2
Application number: PCT/DE1997/002042
Authority: WO
Inventors: Norbert Wulst; Klaus Helbig
Original assignee: Dtm Data Telemark Gmbh
Priority date: 1996-09-13
Filing date: 1997-09-12
Publication date: 1998-03-19
Also published as: AU719803B2; EP0925708B1; NO990506D0; IL121739A0; EP0925708A2; JP2001503209A; CA2265555A1; IL121739A; NO990506L; AU4614797A; WO1998011755A3

Abstract

It is the objective of this invention to create a process and a device which permit increasing the working range of transmission paths between functional units of an ISDN subscriber line with minimum bandwidth relative to the ISDN interface. The invention achieves the objective by means of a process in which (a) the data transmission is done so that the coded data specific to ISDN is converted into binary code on both the network side and the terminal side using a code converter, (b) the entering data of the B channels are prepared in segments of equal length for B1 and B2 channel data in a memory unit and subsequently fed to the transmission device and sent to the receiver side. The data leaving the storage device are checked for consistency and compressed; (c) blocks are formed out of the entering data of the D channel blocks and fed into the transmission device for transmission to the receiver side, (d) the ISDN-specific clock pulses are regained out of the temporal sequence of the transferred data bits on the terminal side or net side, respectively, by means of clock pulse recovery elements, and (e) the received data bits are analyzed, detected D channel blocks are disassembled and fed directly into a code converter, and detected B channel data is decompressed and the binary-coded data converted into coded data specific to ISDN.

Description

Method and device for increasing the range of the transmission path between functional units of the ISDN subscriber line with a minimized

Bandwidth

The invention relates to a method and a device for increasing the range of the transmission path between functional units of the ISDN subscriber line in relation to an ISDN interface, as standardized for example according to CCITT 1.400 - ISDN User Network Interface and 1.430 - Basic User Network Interface. With the invention it is possible to transmit the diverse ISDN services over long distances with a minimized bandwidth.

The ISDN (Integrated Services Digital Network), which in addition to telephony also enables the fast transmission of data, texts and images, provides the option of connecting NT and TE devices and other distribution networks at its interfaces. Regardless of a network connection of ISDN terminal equipment (TE) or network terminations (NT), it is advantageous to extend the range of the transmission path between functional units of the ISDN subscriber connection based on an ISDN interface in order to extend the information in a network over a longer period To be able to pass on the route. However, the range that can be achieved with conventional means is considerably restricted due to the electrical properties of the ISDN interfaces and connection paths.

From DE 44 07 214 Cl a technical solution is known which, despite existing limits of the physical conditions at an interface of an ISDN subscriber line, allows an increase in the range of the transmission path between functional units of the ISDN subscriber line. The ISDN-specific encoded data required or required at the ISDN interfaces are converted into binary-encoded data on both the network and terminal side. The binary-coded data are subjected to block formation and sent to a transmission means for transmission for correspondence on the network or terminal side. Due to the standardized structure, e.g. one ISDN basic access with 2 x 64 kbit s for the B channels or 1 x 16 kbit / s for the D channel and necessary signaling and control information are described in DE 44 07 214

Cl transmit information in a bandwidth of 160 kbit / s via the transmission medium and thus considerable and expensive bandwidth for data transmission z. B. over a

Satellite channel claimed.

However, there is a considerable increase in data transmission, especially via satellite channels

Requirement for shortened bandwidths or for precisely defined bandwidths in a size of, for example, 64 or 128 kbit / s. Operate a number of satellite service providers

Terminals with 64 kbit / s channels.

It is therefore an object of the invention to provide a method and a device which allow the range of the transmission path between functional units of the ISDN subscriber line to be increased with respect to an ISDN interface with a minimized bandwidth. This while maintaining all typical ISDN features, such as:

- Maintaining the network clock

- Multiple access to the interface bus

- Activation and deactivation of the interface.

According to the invention, the task of increasing the range of the transmission path between functional units of the ISDN subscriber line with respect to an ISDN interface with a minimized bandwidth is achieved by a method in which

a) the data is sent on the network side in such a way that the ISDN-specific coded data arriving at an ISDN interface are converted into binary-coded data separately according to B and D channel information by means of a code converter,

b) the accumulated data of the B channels separated according to Bl and B2 channel data, sections of the same length for Bl and B2 channel data in one Storage device provided and then in a step cycle derived from the ISDN network clock alternating Bl and B2 channel data supplied to the transmission means and transmitted via this to the receiver side, the data coming from the storage device being examined for data equality and compressed,

c) blocks are formed from the accumulating data of the D-channel and these are fed to the transmission means for transmission to the receiver side instead of the B-channel data, preferably in the step cycle derived from the ISDN network clock, d) on the terminal side by means of a clock recovery means from the time sequence of the transmitted Data bits, which are recovered for the communication of sender and receiver necessary ISDN-specific clocks and

e) the received data bits are analyzed, recognized D-channel blocks are resolved and fed directly to a code converter and recognized B-channel data is decompressed and buffered separately according to B1 and B2 channel data in a memory device and fed to the code converter in accordance with the recovered clock rate and the binary-coded data converted into ISDN-specific encoded data,

f) the data is sent on the terminal side analogously to method steps a) to c), the cycle specified in method steps b) and c) being that which is recovered after method step d) and

g) the received data bits are analyzed on the network side, recognized D-channel blocks are resolved and fed directly to the code converter, and detected B-channel data is decompressed and buffered separately according to B1 and B2 channel data in a memory device and fed to the code converter in accordance with the ISDN network clock and the binary encoded data can be converted into ISDN-specific encoded data. The compression or decompression of the B-channel data after method step b) is preferably carried out in such a way that the same characters are provided with a repetition counter and an identifier during compression, and character repetitions identified during the decompression are resolved again.

Advantageously, there is no supply of B-channel data to the transmission medium in times when a Bl and / or B2 channel is not used for transmission. Is z. B. only one B-channel is active, only the B-channel data of the active B-channel are processed. The required data rate in the transmission medium is thus reduced to the data rate of the active B channel.

The naturally occurring fluctuations in the required size of the data rate for the transmission of the B-, D-channel information and the compression information are compensated for in the data transmission in that the transmitted binary-coded data on the terminal or network side by means of a storage device organized according to the FIFO principle be buffered to a suitable depth. With the method according to the invention, the bandwidth required for data transmission can thus advantageously be reduced to the net data rate of the B channels to be transmitted.

For the compression, those occurring in the Bl and B2 channel data stream are used

Repetitions of characters used. If such character repetitions are recognized, a correspondingly labeled compression block is formed for the respective channel, in which it is indicated how much identical data was found in the output stream.

A compression block is formed even if the data stream is not reduced as a result. This block is used to synchronize byte limits for the B-channel

Data flow guaranteed.

After method step b), B-channel sections with a fixed length are advantageously formed and transmitted, the minimum length of the D-channel blocks and B-channel

Compression blocks is 1/4 of the B-channel sections and the D-channel blocks can have a multiple of the minimum length.

If D-channel blocks and B-channel compression blocks are formed, the transmission of the B-channel sections is interrupted and instead of the B-channel sections these blocks are interrupted Transmission means for transmission to the receiver side supplied, the transmission of the D-channel blocks preferably taking place. The transmission of the B channel sections is advantageously interrupted at a point that can be divided by 4.

The B channel sections formed are transmitted to the receiver side with a clock derived from the ISDN network clock by means of known transmission devices via satellites or other transmission channels. This bit clock is recovered on the terminal side for the ISDN interface from the bit transmission clock by means of a PLL circuit (Phase Located Loop).

The received data bits are analyzed on the receiver side, recognized D-channel blocks are resolved and the D-channel data are fed directly to the code converter. When the B-channel data is detected, the B-channel compression blocks are resolved, buffered accordingly in accordance with B1 and B2 channel data in the memory device and fed to the code converter in accordance with the recovered clock, and the binary-coded data is converted into ISDN-specifically coded data.

Both the terminal and network-side conversion of the ISDN-specifically encoded data into binary-encoded data is carried out according to known principles by means of a code converter, preferably an ISDN subscriber access controller.

If several channels are used for transmission from the transmission medium, the network and terminal side can be divided and assigned according to the B channels to be transmitted.

Advantageously, the method according to the invention can also be carried out in such a way that, when the ISDN interface is not active, the transmission of digital, serial data takes place via the transmission means without code conversion. This is possible in particular if several channels are provided by the transmission means. The connections to at least one transmission channel are used as an interface for the exchange of digital, serial data and the other transmission channels for the transmission of this data.

According to the invention, the method for increasing the range of the transmission path between functional units of an ISDN subscriber line is implemented by a device which comprises both a terminal and a network device for protocol conversion and a transmission channel. The transmission channel consists of transmission devices known per se and the medium used for the transmission, for example a satellite channel with the corresponding transmitting and receiving devices and the modems required for this. The transmission channel can advantageously consist of several individual channels. If the transmission channel consists of several individual channels, the connections to at least one transmission channel can advantageously be used as an interface for the exchange of digital, serial data. This enables the transmission of digital, serial data via the other transmission channels at times when the ISDN interface is not active.

The devices for protocol conversion communicate with one another via the transmission channel. The devices for protocol conversion are preferably constructed identically and can function both in the master mode and in the slave mode, the network-connected device for protocol conversion in the master mode and the terminal-side device for protocol conversion operating in the slave mode.

The protocol conversion facilities essentially consist of

an ISDN interface module (1), a microcomputer (6), one or more interface modules (2) for the transmission channel X, a module for clock generation (3), a mode switch (5), a power supply (4), and corresponding electrical connections and a bus for the address and

Data exchange.

The microcomputer (6) is connected via a bus to the ISDN interface module (1) and one or more interface modules (2) for connection to the transmission channel X.

The module for clock generation (3) is connected to the interface module (1) and with the interface modules (2) for connection to the transmission channel (X) as well as with the microcomputer (6) and is suitable from the chronological sequence of the transmitted data bits Communication between sender and receiver to recover the ISDN-specific clocks required The switch (5) for the mode setting (master / slave) acts on the power supply (4), on the interface module (1) and on the module (3) for clock generation. The mode switch (5) has an additional switching function for operation for protocol conversion via one or more interface modules (2) and the assignment of corresponding transmit clocks for a common operation.

The power supply (4) supplies the circuit with voltage and, when the protocol converter is operating in slave mode, generates the supply voltage for network-independent devices.

The ISDN interface module (1) electrically converts the ISDN interface into a binary-coded form and vice versa. The binary data and the necessary control information are exchanged via the bus between the interface module (1), the microcomputer (6) and the interface modules (2). The ISDN interface module (1) is constructed from an ISDN interface interface and a circuit for converting the ISDN-specifically encoded data into binary-encoded data, for example an ISDN subscriber access controller (ISAC circuit). The interface modules (2) for transmission on the X channel each consist of an interface interface and a serial input-output module SIO.

The microcomputer (6) consists of a microprocessor, a ROM for storing the

Program codes, a RAM as working memory and a BUS. Over the extended

The microcomputer (6) is connected to the ISAC circuit in the interface module (1) and to the serial input-output modules SIO in the interface modules (2).

The processor in the microcomputer (6) controls the function of the clock module (3),

ISAC circuit in the interface modules (1) and SIO in the interface modules (2) in a known manner by setting the registers provided therefor

Components.

The microcomputer (6) is suitable for the accumulating data of the B channels according to Bl and B2

To separate channel data, sections of the same length for Bl and B2 channel data in its

Provision storage, then compress and in conjunction with the

Exchange clock module (3) with the interface modules (2) and from the

Interface modules (2) to receive received data and to the interface module

(1) to be handed over. On the network side, the device for protocol conversion in master mode works as follows:

In the interface module (1), the mutual conversion of the signal levels from the ISDN interface to the signal levels required by the ISAC module takes place in the ISDN interface.

The mode switch (5) switches the ISAC module in the interface module (1) to TE mode (terminal mode). In this mode, the ISAC circuit generates a 512 kHz clock at the DCL output. If the ISDN interface is active, the 512 kHz clock is derived synchronously from the bit clock of the ISDN interface.

The 512 kHz clock from the ISAC circuit of the ISDN interface is used in the module for clock generation (3) controlled by the processor in the microcomputer (6) in order to transmit the transmission clock according to an additional switch position in the mode switch (5) for the respective interface modules (2) produce.

The ISAC circuit in the interface module (1) converts the ternary coded B and D channel signals from the ISDN interface into binary coded signals and stores them in its registers byte by byte. Conversely, the block converts the binary-coded B and D-channel bytes entered by the processor in the microcomputer (6) into ternary signals and sends this data to the interface of the interface module (\) for transmission on the ISDN interface.

The ISAC circuit signals by means of a register that it is ready to take over a new Bl and B2 channel byte and at the same time a complete Bl and B2 channel byte is ready for takeover by the processor in the microcomputer (6) . The processor in the microcomputer (6) polls the signaling register of the ISAC circuit cyclically and separates the B-channel bytes into B1 and B2 channel sections in its working memory.

The ISAC circuit uses another register to signal when D-channel data has been received from the ISDN interface. The processor in the microcomputer (6) also polls this signaling byte cyclically and forms D-channel blocks from the accumulating D-channel data.

If the processor in the microcomputer (6) has received a D channel block from the remote station, this is resolved and sent to the ISAC circuit for forwarding to the ISDN interface.

The processor in the microcomputer (6) forms sections from the B-channel data adopted by the ISAC circuit and stores them in its RAM. The microcomputer selects an SIO according to the logical address and polls the register of this SIO cyclically. The SIO shows in its register when the next part of the data should be transferred so that the transfer does not stop. The processor in the microcomputer (6) feeds the addressed SIO in the interface module (2) accordingly further data parts.

The processor passes the SIO in the respective interface module (2) in consecutive order data parts of the ISDN interface. The ISDN interface works synchronously on the basis of the ISDN network clock, so that the data parts also correspond to those in the mode switch

(5) for the respective interface module (2) set transmit clock are transmitted synchronously.

Before the microcomputer (6) transfers B-channel sections to the addressed SIO, the buffered B-channel data are analyzed. It forms compression blocks from compressible data and transmits them instead of the B-channel sections. The relative address in the B-channel section is supplied in the compression block.

The microcomputer (6) forms D-channel blocks from the available D-channel data and preferably passes them to the addressed SIO instead of the B-channel sections, the relative address in the B-channel section also being transmitted.

In the opposite direction, the addressed SIO in the interface module (2) receives bit serial data via the interface in the interface module (2). When the first data part is received in the SIO, corresponding signaling bits are set in a register of the SIO. The processor of the microcomputer (6) polls this register cyclically and analyzes the received data. B-channel data are buffered separately according to Bl and B2 channel data in the RAM of the microcomputer (6). Detected D-channel blocks are resolved and transferred to the D-channel register of the ISAC circuit in the interface module (1). Detected B-channel compression blocks are resolved and in the RAM of the microcomputer

(6) temporarily stored and forwarded to the ISAC circuit in the interface module (1).

On the terminal side, the protocol conversion device in slave mode works as follows:

In the interface module (1), the mutual conversion of the signal levels from the ISDN interface to the signal levels required by the ISAC circuit block takes place in the interface interface. The mode setting (5) switches the ISAC circuit in the interface module (1) to NT mode (Network Terminal mode). In this mode, the ISAC circuit requires synchronous clocks at the DCL inputs of 512 kHz, FSC1 and FSC2 of 8 kHz. From these, the ISAC circuit derives the frame synchronous and bit synchronous clocks for the ISDN interface.

In the module for clock generation (3), the clock is recovered from the bit clock of a selected interface module (2), from which in the module for clock generation (3) a clock 512 kHz is generated by means of a PLL operating according to known principles and a clock of 8 kHz is generated therefrom by division becomes. These clocks are supplied to the corresponding inputs of the ISAC circuit in the interface module (1).

Microcomputer (6), ISAC circuit in the interface module (1) and SIO in the interface module (2) work together in an analogous manner as in the master device in the forwarding of the B and D channel data between the ISDN interface and the X channel .

Devices for converting the protocol can advantageously be constructed both with an interface module (2) and with a plurality of interface modules (2). The mode switch (5) then has an additional switching function for operation for protocol conversion via one or more interface modules (2) and the assignment of corresponding transmit clocks for a common operation.

With the method according to the invention and the device according to the invention, it is possible to pass on the various ISDN services over the interface over long distances in a minimized bandwidth without having to convert to another network. This enables it to remain in the used ISDN network, which does not affect the quality of the transmission services.

If the transmission channel consists of several individual channels, the connections to at least one transmission channel can advantageously be used as an interface for the exchange of digital, serial data. For this purpose, the connection of an interface module (2) is connected as an interface for digital, serial data and allows the exchange of digital, serial data via the other transmission channels in times when the ISDN interface is not active.

The microcomputer (6) recognizes the state of the ISDN interface by evaluating the D-channel information. If the interface is deactivated, the microcomputer (6) takes over data from the interface module (2), which in this mode of operation is connected as an interface for digital, serial data, and transfers this to the further interface module (2) for transmission on the transmission channel X. If the ISDN interface is activated, the interface module (2 ), which is switched for the exchange of digital, serial data, switched off by the microcomputer (6). The protocol conversion devices then operate as described.

Exemplary embodiments of the invention are explained in more detail with reference to the attached drawings. Show

Fig. 1 is a block diagram of a device for protocol conversion

Fig. 2 shows a device for increasing the range of the transmission path between functional units of the ISDN subscriber line

3 shows a device for increasing the range of the transmission path between functional units of the ISDN subscriber line with the protocol converter assigned to the respective transmission channel on the terminal side

Fig. 4 shows a device for increasing the range of the transmission path between functional units of the ISDN subscriber line with interfaces for the exchange of digital, serial data

1 shows a device for protocol conversion in the block diagram.

The microcomputer (6) consists of a microprocessor, designed as .Am 188 ^τ EM, a ROM for storing the program code, a RAM as working memory, and a BUS.

Via the extended bus of the microcomputer, it is connected to an SIO module designed as SAB 82532 in two interface modules (2) and to the ISAC circuit designed as PEB 2086 in the interface modules (1).

The processor in the microcomputer (6) controls the function of the components PEB 2086 and SAB

82532 by setting the register provided in these components. The processor also queries the status of these components and exchanges data via registers of these components. The ISDN interface is activated / deactivated by the PEB 2086 in the interface module (1). The status of the ISDN interface can be read from registers of the PEB 2086. The processor in the microcomputer (6) cyclically polls the registers of the PEB 2086, which indicate the status of the ISDN interface.

On the network side, the device according to FIG. 1 operates in master mode as follows:

In the interface module (1), the mutual conversion of the signal levels from the ISDN interface to the signal levels required by the PEB 2086 module takes place in the ISDN interface.

The PEB 2086 module in the interface module (1) is switched to TE mode (terminal mode) by means of a mode switch (5). In this mode, the PEB 2086 generates a 512 kHz clock at the DCL output. If the ISDN interface is active, the 512 kHz clock is derived synchronously from the bit clock of the ISDN interface.

The clock 512 kHz of the interface module is passed to the module for clock generation (3). The 512 kHz clock from the PEB 2086 of the ISDN interface, controlled by the processor, is used in the clock generation module (3) in order to generate the predetermined transmission clock of 64 kbit / s for the respective SIO by division.

The PEB 2086 in the interface module (1) converts the temporarily coded B and D channel signals from the ISDN interface into binary coded signals and stores them in its registers byte by byte. Conversely, the module converts the binary-coded B and D-channel bytes entered by the processor of the microcomputer (6) into ternary signals and sends this data to the interface of the interface module (1) for transmission to the ISDN interface.

The PEB 2086 uses a register to signal that it is ready to accept a new Bl and B2 channel byte and at the same time a complete Bl and B2 channel byte to be accepted by the processor. The processor of the microcomputer (6) polls the signaling register of the PEB 2086 cyclically and accepts the finished B-channel bytes in its working memory or transfers the B-channel bytes.

The PEB 2086 uses another register to signal when a D-channel frame has been received by the ISDN interface. The processor also polls this signaling byte cyclically, accepts the D-channel data on its working memory and forms D-channel blocks. If the processor has received a D-channel block from the remote station, it is resolved and sent to the PEB 2086 for forwarding to the ISDN interface. The processor of the microcomputer (6) forms 32-byte Bl and B2 sections from the bytes taken over from the PEB 2086 and temporarily stores them in RAM.

The microcomputer selects an SIO according to the logical address and polls the register of this SIO cyclically. The SIO shows in its register when the next part of the data should be transferred so that the transfer does not stop. The processor in the microcomputer (6) feeds the addressed SIO in the interface module (2) accordingly further data parts.

The processor passes the SIO in the respective interface module (2) in consecutive order data parts of the ISDN interface. The ISDN interface works synchronously on the basis of the ISDN network clock, so that the data parts are also transmitted synchronously in accordance with the transmission clock of 64 kHz set for the respective interface module (2) in the mode switch (5).

Before the microcomputer (6) transfers B-channel sections to the addressed SIO, the buffered B-channel data are analyzed. It forms compression blocks of 8 bytes in length from compressible data, interrupts the transfer of B-channel sections to the addressed SIO and transmits these instead of the B-channel sections.

The relative address in the B-channel section is supplied in the compression block. At the same time, this block is used for byte synchronization.

From the existing D-channel data, the microcomputer (6) forms D-channel blocks with a length of 8 bytes or a multiple thereof and transfers them preferably to the addressed SIO instead of the B-channel sections, the relative address in the B-channel section is transmitted with. The transmission of the D-channel blocks is also used for byte synchronization.

In the opposite direction, the addressed SIO in the interface module (2) receives bit serial data via the interface in the interface module (2). When the first data part is received in the SIO, corresponding signaling bits are set in a register of the SIO. The processor of the microcomputer (6) polls this register cyclically and analyzes the received data. B-channel data are buffered separately according to B1 and B2-channel data in the RAM of the microcomputer (6). Detected D-channel blocks are resolved and transferred to the D-channel register of the ISAC circuit in the interface module (1). Detected B-channel compression blocks are resolved and buffered in the RAM of the microcomputer (6).

The B-channel sections are held in a FIFO queue of suitable depth on the transmitting and receiving sides in order to compensate for the increased need for transmission rate, which is caused by the occurrence of D-channel blocks. The data rate is kept constant on average by compressing the B-channel data.

On the terminal side, the device according to FIG. 1 operates in slave mode as follows:

The mode setting (5) switches the PEB 2086 module in the interface module (1) to NT mode (Network Terminal mode). In this mode, the PEB 2086 requires synchronous clocks at the DCL inputs of 512 kHz, FSC1 and FSC2 of 8 kHz. From these, the PEB 2086 derives the frame synchronous and bit synchronous clocks for the ISDN interface.

Microcomputer (6), ISAC circuit in the interface module (1) and SIO in the interface module (2) work together in an analogous manner as in the master device in the forwarding of the B and D channel data between the ISDN interface and the X channel . With the device according to FIG. 1, it is possible to pass on the various services of the ISDN over the interface over long distances in a bandwidth of 64 kbit / s per B-channel without having to convert to another network. A stay in the used ISDN network is made possible and the quality of the transmission services is not impaired.

2 shows a device for increasing the range of the transmission path between functional units of the ISDN subscriber line in relation to an S ₀ - Interface again. Starting from a network ISDN, via an interface U _ko to one

Network termination NT1 is a device on the network side at the interface S ₀

Subordinate protocol conversion PW, which over two transmission channels with one

Device for protocol conversion PW communicates on the terminal side and provides the interface S _{0 on the} terminal side. At the terminal end, for example, a switching system

(NT2) or terminals (TE) can be operated immediately.

The S ₀ device connected on the network side works in master mode, the S ₀ device connected on the terminal side works in slave mode. The device working in master mode behaves towards the ISDN network like a terminal (TE), the device working in slave mode like a network termination (NT).

Between the two devices for protocol conversion (PW) connected via two transmission channels used in parallel, data exchange takes place by means of bit-serial synchronous transmission of B-channel sections for B1 and B2 with a length of 32 bytes. Similar output data are transmitted as a compression block and D-channel data are transmitted as a D-channel block. These blocks are also used for byte synchronization.

The device for protocol conversion PW in master mode always reactivates the S ₀ interface when it is not active. It only transfers data when the S _o interface is active.

The device for protocol conversion PW in slave mode reactivates the S ₀ interface when it is not active and the device is also receiving data from the master device. It deactivates the S ₀ interface when it receives no data from the master device.

With the device according to FIG. 2, it is possible to pass on the diverse services of the ISDN over the interface over long distances in a bandwidth of 64 kbit / s per B-channel without having to convert to another network. A stay in the used ISDN network is made possible and the quality of the transmission services is not impaired. 3 shows, analogously to FIG. 2, a device for increasing the range of the transmission path between functional units of the ISDN subscriber line in relation to an ISDN interface. In contrast to FIG. 2, a protocol converter is assigned to each transmission channel on the terminal side. This enables communication to be carried out separately for each Bl and B2 channel over 64 kbit / s at separate locations.

4 shows, analogously to FIG. 2, a device for increasing the range of the transmission path between functional units of the ISDN subscriber line in relation to an ISDN interface S ₀ . Compared to Fig. 2, the interface to the transmission channel X2 as a connection to a digital, serial data source, for. B. LAN or a PC used. In the times when the ISDN interface S _{0 is} not active, digital, serial data can then be exchanged via the transmission channel XI.

The microcomputers (6) of the protocol converter (PW) recognize the state of the ISDN interface S ₀ by evaluating the D-channel information. When the interface S _{0 is} deactivated, the microcomputer (6) takes over data from the interface module (2), which in this mode of operation is used as Interface for the exchange of digital, serial data is switched, and passes this to the further interface module (2) for transmission on the transmission channel XI. If the ISDN interface S _{0 is} activated, the microcomputer (6) switches off the interface module (2) which is switched for the exchange of digital, serial data. The device for protocol conversion then works as described in FIG. 2.

By using the protocol converter described in FIG. 4, the switching function of direct access to an ISDN network can be integrated in existing data connections.

Claims

claims

1. A method for increasing the range of the transmission path between functional units of the ISDN subscriber line with a minimized bandwidth, characterized in that

b) the accumulating data of the B channels is separated into Bl and B2 channel data, sections of the same length are provided for Bl and B2 channel data in a storage device and then in a step cycle derived from the ISDN network clock alternating between Bl and B2 Channel data is fed to the transmission means and transmitted to the receiver side via this, the data coming from the storage device being examined for data equality and compressed,

c) blocks are formed from the accumulating data of the D channel and these are fed to the transmission means for transmission to the receiver side in preference to the step cycle derived from the ISDN network clock, instead of the B channel data,

d) on the terminal side by means of a clock recovery means from the chronological sequence of the transmitted data bits, the ISDN-specific clocks necessary for the communication between transmitter and receiver are recovered and

e) the received data bits are analyzed, recognized D-channel blocks are resolved and fed directly to a code converter, and recognized B-channel data is decompressed and separated according to Bl and B2 channel data in one Storage device buffered and fed to the code converter according to the recovered clock and the binary coded

Data is converted into ISDN-specific encoded data,

g) the received data bits are analyzed on the network side, recognized D-channel blocks are resolved and fed directly to the code converter, and detected B-channel data is decompressed and buffered separately according to B1 and B2 channel data in a memory device and fed to the code converter in accordance with the ISDN network clock and the binary encoded data can be converted into ISDN-specific encoded data.

2. The method according to claim 1, characterized in that the compression or decompression of the B-channel data after the method steps b) or e) is carried out so that when the same characters occur, a B-channel compression block with a repeat counter and an identifier for the respective channel is formed and character repetitions recognized during decompression are resolved again.

3. The method according to claim 1 and 2, characterized in that B-channel sections are formed with a fixed length, the minimum length of the D-channel blocks and B-channel compression blocks is 1/4 of the B-channel sections and the D - Channel blocks have a multiple of the minimum length.

4. The method according to claim 1 to 3, characterized in that in the formation of D-channel blocks and B-channel compression blocks, the transmission of the B-channel sections is interrupted at a position divisible by 4 and this instead of the B-channel sections the transmission means be transmitted for transmission to the receiver side, with the D channel blocks being preferred.

5. The method according to claim 3, characterized in that a B-channel compression block is formed as an aid to synchronization on byte boundary even if the data stream is not reduced thereby.

6. The method according to claim 1, characterized in that in the times in which a Bl and / or B2 channel is not used for transmission, there is no supply of B channel data to the transmission means.

7. The method according to claim 1, characterized in that at the times when the ISDN interface is not active, digital, serial data are exchanged without code conversion via the transmission means.

8. Device for protocol conversion for increasing the range of the transmission path between functional units of the ISDN subscriber line, consisting essentially of an ISDN interface module (1), a microcomputer (6), one or more interface modules (2) for the transmission channel X, one Module for clock generation (3), a mode switch (5), a power supply (4) and corresponding electrical connections and a bus for address and data exchange, the interface module (1) being suitable for both ISDN-specific encoded data in binary code To convert data and vice versa binary-coded data into ISDN-specific coded data, the microcomputer (6) being connected and suitable via the bus with the ISDN interface module (1) and with the interface modules (2) for connection to the transmission channel X. to separate the accumulating data of the B channels according to Bl and B2 channel data, section Sect Itte to provide for Bl and B2 channel data in its memory, then compress it and exchange it in connection with the clock module (3) with the interface module (2), and is suitable for accepting data received from the interface module (2) and to the interface module (1) to be transferred, the switch (5) for the mode setting (master / slave) acting on the power supply (4), on the interface module (1) and on the module (3) for clock generation and one has additional switching function for operation for protocol conversion via one or more interface modules (2) and the assignment of corresponding transmit clocks, the power supply (4) supplying the circuit with voltage and, if the protocol converter is operating in slave mode, generating the supply voltage for network-independent end devices, and wherein the module for clock generation (3) with the interface modules (1), with the interface module (2) for connection to the transmission channel (X) and with the microcomputer (6) is connected and suitable from the time sequence of the transmitted data bits to

Communication between sender and receiver to recover necessary ISDN-specific clocks.

9. Device for protocol conversion according to claim 7, characterized in that an interface module (2) is connected as an interface for the exchange of digital, serial data and a further interface module (2) realizes the interface to the transmission channel X.

10. The device for realizing the method according to claim 1, characterized in that it consists of terminal and network connected devices for protocol conversion with the ISDN interfaces and associated transmission channel from the transmission device and transmission medium and the devices for protocol conversion communicate with each other via the assigned transmission channel , and that the devices for protocol conversion are constructed both in the master and slave mode or in the master or in the slave mode, the network-connected device for protocol conversion in the master mode and the terminal-connected device for protocol conversion in the slave mode being connected.

11. The device according to claim 8, characterized in that the transmission channel X is constructed from one channel or several channels.

12. The apparatus according to claim 9, characterized in that the connections to at least one transmission channel X as an interface for the exchange digital, serial data are switched and the transmission of digital, serial data is permitted over the other transmission channels at times when the ISDN interface is not active.